[3][1] Some sources give Knut's spouse as Danish noble woman Helena Pedersdatter Strange ( c. 1200–1255).

However this theory has been challenged by Hans Gillingstam [sv] (1925–2016), who instead believed that he was married to an unknown woman from the House of Bjälbo, evidenced by the coat of arms on the tomb cover of his son Holmger.

[3][5] Knut Långe was probably a member of the council that ruled Sweden from 1222 to 1229, during the minority of King Erik Eriksson.

Despite this error, the note, when considered alongside other sources, has been interpreted as a possible indication that Knut was co-regent with Erik Eriksson during part of his reign.

[3] Knut's reign likely saw the revision of some Swedish laws: creditors could no longer enter the homes of debtors to collect debts without the assistance of a government official, and the king was required to hold judicial reviews at least every third year.